arXiv subjects

R Simpson

Publications and source records attributed to R Simpson.

3 recordsLinked to original sources

arXiv2026

Laboratory observation of collective beam-plasma instabilities in a relativistic pair jet

We report on a measurement of collective behavior in a relativistic electron-positron pair plasma produced in the laboratory. Using the Fireball platform at CERN's HiRadMat facility, 440 GeV protons were used to generate an ultra-relativistic, charge-neutral electron-positron pair beam that propagated through an ambient RF discharge plasma. Magnetic-field amplification due to a beam-plasma instability was diagnosed using a high-sensitivity Faraday-rotation probe, supported by detailed characterization of the diagnostic impulse response. The measured path-integrated magnetic field agrees quantitatively with predictions from particle-in-cell simulations. The results provide a critical benchmark for models of relativistic beam-plasma interactions in astrophysical contexts such as blazar jets and pulsar-wind nebulae.

physics.plasm-ph↗

arXiv2020

Thermometry of intermediate level nuclear waste containers in multiple environmental conditions

Intermediate level nuclear waste must be stored until it is safe for permanent disposal. Temperature monitoring of waste packages is important to the nuclear decommissioning industry to support management of each package. Phosphor thermometry and thermal imaging have been used to monitor the temperature of intermediate level waste containers within the expected range of environmental storage conditions at the Sellafield Ltd site: temperatures from 10 {\deg}C to 25 {\deg}C and relative humidities from 60 %rh to 90 %rh. The feasibility of determining internal temperature from external surface temperature measurement in the required range of environmental conditions has been demonstrated.

physics.ins-det↗

arXiv2018

Thermometry of intermediate level waste containers using phosphor thermometry and thermal imaging

Intermediate level waste containers are used for the storage of an assortment of radioactive waste. This waste is heat-generating and needs monitoring and so this work was undertaken to determine whether the mean internal container temperature can be inferred from the temperature of the vent. By using two independent thermometry techniques, phosphor thermometry and thermal imaging, the internal temperature was demonstrated to be proportional to the vent temperature as measured by both methods. The correlation is linear and given suitable characterisation could provide robust indication of the internal bulk temperature.

physics.ins-det↗